The invention concerns a device for fluid bed techniques, in particular for the coating of tablets or the like. The device has a container through which an adjustable gas current flows to move the tablets or any similar objects through a processing zone.
In fluidized bed techniques, the container acts as a processing zone in which the tablets or similar objects are processed, dried, and/or treated. In order to optimize the processing of the tablets or the like, a certain spatial extent of the processing zones and/or of the extension of the fluidized bed is required, particularly with regard to the "flight altitude" of the tablets or the like. An analogous rule applies to fluidized bed granulation. One means of controlling the fluidized bed is by varying the gas flow into the processing zone. As is well known, this can be accomplished by manually changing the air volume, e.g. by means of an air slide, until the desired height of the fluidized bed has been achieved. The modification of the setting, as well as the monitoring of the fluidized bed zone, usually takes place visually by an operator. However, in order to maintain a constant altitude of the fluid bed zone, a continuous control is necessary, since, under certain circumstances during the treatment process, modifications of the material to be processed may occur that necessitate corresponding modifications of the "flight altitude" of the tablets. It is also necessary to make different adjustments in situations where the material to be processed is different. Consequently, for good results during processing, expensive and cumbersome monitoring and manual setting by an operator are necessary. However, even careful monitoring by an operator cannot insure that an optimal setting is maintained continuously throughout the processing period. Optical illusions may affect the operator during visual control which can result in processing the tablets or the like in an undesirable manner.